The Demographic Transition,with Data from Brazil

Abstract

The demographic transition—the process through which declines in mortality precede declines in fertility, leading to a period of population growth and the long-term restructuring of the age composition—holds remarkable power to explain the state of our social world. In this visualization, I employ Brazilian demographic measures dating back to the 1870s to depict the interplay between mortality, fertility, growth rates, dependency ratios, and total population size within a single three-panel figure with a shared time axis. Over the course of nearly two centuries, fertility and mortality differentials contribute to a staggering 18-fold increase in Brazil’s population size and a dramatic rise in the proportion elderly. Although the data are drawn from a single country, Brazil’s patterns of demographic change are representative of those experienced in many other populations. A graph of demographic transition-era population dynamics alongside an understanding of various world regions’ positions along the x-axis can help to answer innumerable questions of great social importance.

Keywords

demographic transition dependency ratios Brazil population size growth rate

Before the start of the demographic transition, life was short, births were many, growth was slow and the population was young.

—Lee (2002: 167)

So begins Ron Lee’s (2002) marvelous article, “The Demographic Transition: Three Centuries of Fundamental Change,” published two decades ago in the Journal of Economic Perspectives. In Lee’s Figure 6, he plots real and projected data from India 1900 to 2100 in five adjacent graphs to guide readers through the population dynamics associated with a classic demographic transition. With those graphs as my inspiration and employing Brazilian demographic measures dating back to the 1870s, this data visualization (Figure 1) reimagines Lee’s depiction of the interplay between mortality, fertility, growth rates, dependency ratios, and total population size. Combining historical demographic measures from 1870 to 1949 (Chesnais 1992) with United Nations measurements and projections from 1950 to 2100 (United Nations Department of Economic and Social Affairs, Population Division 2022), I have created a single three-panel figure that depicts the progression of the demographic transition in Brazil specifically but also across the world more broadly.

Figure 1.

Before the onset of the demographic transition, births are kept mostly in check by deaths (upper panel), meaning that the overall growth rate is relatively low (second panel) and population sizes are small (lower panel). By the late nineteenth century, mortality is falling due to improvements in health (e.g., sanitation), but fertility remains high. As mortality diverges from fertility, the growth rate begins to rise, reaching a peak level around 1960, when crude birth and death rates are at their most different. The next stage of the transition is marked by the onset of declining fertility, driven by factors such as decreased demand for children and changing gender norms. Here, falling fertility rates begin to close in on already low mortality rates (upper panel), leading to a decline in overall growth rates (second panel). Despite the decelerating rate of growth, this stage marks an era of enormous overall increases in population size, from around 6 times the pre-transition population size before the onset of fertility declines to around 18 times the pre-transition size only 70 years later. Finally, the projected post-transition stage represents a period of stable, or perhaps declining, population sizes, as fertility rates remain low and crude mortality rates rise (upper panel) due to the aging population (lower panel). Indeed, only 1 in 10 Brazilian residents was elderly in the year 2000, compared with a projected 30 percent elderly by the latter half of the twenty-first century (lower panel).

My graph diverges from Lee’s (2002) in a few key areas. First, I display fertility and mortality as crude rates (expressed as annual events per 1,000 people) as opposed to synthetic cohort measures (life expectancy and total fertility rate) due to the ease with which crude rates can be subtracted from one another to calculate the rate of natural increase. With this methodological choice, I can combine births and deaths into a single panel, allowing for visual comparisons of their slopes. I display youth and old age dependency outcomes as population sizes rather than ratios, which allows me to consolidate total population size and number of dependents into a single panel depicting population as the sum of three age groups (youth, adult, and elderly). Finally, my figure stacks all its panels along a single time axis, an ideal choice for observing population dynamics at a given time point.

I plot data from Brazil due to the early availability of its crude data, reflecting a period when high fertility was nearly offset by high mortality. For simplicity, I extend the earliest observed birth rates backward to be flat over time. Regarding mortality, I assume that pre-transition mortality trends fluctuated from year to year (Lee 2002). Brazilian death rates were already declining between the earliest recorded data points (Chesnais 1992), suggesting that the onset of the country’s transition may have actually begun prior to 1870.

Although the data are drawn from a single country, Brazil’s patterns of demographic change are representative of those experienced in many other countries. Across the globe, the tendency for mortality to decline before fertility has powerfully altered the population structure of our social world.

Supplemental Material

sj-docx-1-srd-10.1177_23780231241259620 – Supplemental material for The Demographic Transition, with Data from Brazil

Supplemental material, sj-docx-1-srd-10.1177_23780231241259620 for The Demographic Transition, with Data from Brazil by Sara Lopus in Socius

Footnotes

ORCID iD

Sara Lopus

Supplemental Material

Supplemental material for this article is available online.

Author Biography

Sara Lopus is an associate professor in the Department of Social Sciences at Cal Poly San Luis Obispo. A demographer by training, she studies topics including marriage, parenthood, and household composition. She also researches social-environmental problems, such as urban and agrarian water insecurity. She is currently preparing to travel as a Fulbright Scholar to Brazil, where she will study household investments in children’s education. A former student of Ron Lee, Sara appreciates all that he taught her about kindness, patience, and, of course, demography. She is also grateful to Jane Lopus and Maggie Frye for their thoughtful feedback on this data visualization.

References

Chesnais

Jean-Claude

. 1992. The Demographic Transition: Stages, Patterns, and Economic Implications: A Longitudinal Study of Sixty-Seven Countries Covering the Period 1720-1984. New York, NY: Oxford University Press.

Lee

Ronald

. 2002. “The Demographic Transition: Three Centuries of Fundamental Change.” Journal of Economic Perspectives 17(4):167–90.

United Nations Department of Economic and Social Affairs, Population Division. 2022. “World Population Prospects 2022: Demographic Indicators.” https://population.un.org/wpp/.